From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7961117BB4 for ; Sun, 25 Feb 2024 16:51:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708879890; cv=none; b=MPH+9s/IOmTMznL9ML12kLgPNtPxGCjTyfY0qyrBq8aRcesAeUPtIhuBpnEQ6zVySEHGxbCSG0t38Up2amPnlyhFA8xCWLS0ADoj8Ev3dm3sfwoTLVrHx+szGO00K6Ai6MM2/VcvpGkIhO1q5PO8Rw25pCIDE1yyFcp4bsPr8ig= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708879890; c=relaxed/simple; bh=bKvF/hxZA+IOkRgFlAL5neUWGwYrfVAX96LrV2VLkLE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DEr2F5IskS9Rps2Yvh/SKto6d1P4zy3F5/uFWD4CjEkG4i9V2E7G8bE/KkBy+YrOWxjenhFIRDal1DiHvrFiXcqfcisTrMY+5tUGiAkmvHWTSm2N7z4p+L/0J7TlZpcctFEUBLDAKuSRsKAL3WdQNW/uGn58sxpqw45wpDQaJHk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tBmWlBkP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tBmWlBkP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5D93C433C7; Sun, 25 Feb 2024 16:51:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708879890; bh=bKvF/hxZA+IOkRgFlAL5neUWGwYrfVAX96LrV2VLkLE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tBmWlBkPnSs3oGuBtqaTXgP7mbaeTXZwI0MeHopYOa/A6ONZiwsRRRPhAinYeidc2 dzm9FdZkEMZd1Lyotih2vQbuQROqyHXgBKkqrW2ItomAR3mn8hGIK5Oe7MUUWMBBxN PYdqfkYxInh7xAIaE0o71rXCaDPoHEdmDFGX6aoBHeIRaLhuCBdDm9RMa72uFvGTEP +jDRUHkYNUdKRs4nKSGiXxoN1BfewT+lbpUWghKSVX3dgllPHnwDjN2uT3wkux3Ooi zYeEijKPYOH7LmE1paHYDmjc6qbiVIWKEmQ1fToEbPoAM1UDc7W7pyFXmvIxGfXG9w KH6OtWKGOoXAw== Date: Sun, 25 Feb 2024 08:51:28 -0800 From: Eric Biggers To: Zorro Lang Cc: David Sterba , fstests@vger.kernel.org Subject: Re: Dangerous commands (was:[ANNOUNCE] fstests: for-next branch updated to v2024.02.04) Message-ID: <20240225165128.GA1128@sol.localdomain> References: <20240221140951.GJ355@suse.cz> <20240225151616.owk5v4ioplhrioe6@dell-per750-06-vm-08.rhts.eng.pek2.redhat.com> Precedence: bulk X-Mailing-List: fstests@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240225151616.owk5v4ioplhrioe6@dell-per750-06-vm-08.rhts.eng.pek2.redhat.com> On Sun, Feb 25, 2024 at 11:16:16PM +0800, Zorro Lang wrote: > On Wed, Feb 21, 2024 at 03:09:51PM +0100, David Sterba wrote: > > Hi, > > > > reading [1] and how late it was found that effectively a "rm -rf /" can > > happen makes me worried about what I can expect from fstests after git > > pull. Many people contribute and the number for custom _cleanup() > > functions with unquoted 'rm' commands is just asking for more problems. > > > > [1] https://lore.kernel.org/all/20240205060016.7fgiyafbnrvf5chj@dell-per750-06-vm-08.rhts.eng.pek2.redhat.com/ > > > > Unquoted arguments in shell scripts is IMO a big anti-pattern, > > unfortunately present everywhere in xfstests since the beginning. > > Rewriting all scripts would be quite a lot of work, could you at least > > provide safe versions of the cleanup helpers? > > Hi David, > > Thanks for taking care about it :) > > > > > For example: > > > > _rm_tmp() { > > rm -rf -- $tmp > > It's "$tmp.*" > > May I ask what problem does the "--" hope to avoid? If the "$tmp" is empty, > "rm -rf" and "rm -rf --"" looks like both doing nothing. So what kind > of situation does the "--" hope to fix? > > The root problem in above [1] is about "${FOO}*". If someone does "rm -rf ${FOO}*" > in its custom _cleanup_xxxxx function, then it's dangerous if "$FOO" is empty. > > I thought some ways to avoid that: > 1) Try to avoid doing rm -rf ${FOO}*, if not necessary. > 2) Must checks [ -n "$FOO" ] before doing any rm -rf ${FOO}* > 3) Someone's custom _cleanup_xxxxx better to be called before default _cleanup > does "cd /". > 4) Think about bringing in someone "Static program analysis" tool about bash > script, but I don't know if there're someone good, feel free to give me > suggestions. "--" prevents the following arguments from being interpreted as options if they begin with "-". That's a good practice, but it doesn't help with ${FOO} being empty. To cause the script to exit if ${FOO} is empty, it can be written as ${FOO:?}. Alternatively, 'set -u' can be used. - Eric